EO Capability Benefits
Digital Elevation Models (DEMs) are versatile tools with a wide range of applications across various industries and scientific disciplines. Their ability to represent the Earth’s surface in a digital format makes them invaluable for numerous purposes. They find constant application when landforms, slopes and drainage patterns need to be understood. Reliable Digital Elevation Models support water flow modelling and the delineation of watersheds, making them essential tools to accurately assess hazard exposures such as landslides and floods. Urban and infrastructure planners also use DEMs to design infrastructure projects and assess the impact of new developments on the built form. Height information from a normalised Digital Surface Model can be added to 2D building footprints to create simple 3D city models at scale.
EO Capability Description
A Digital Elevation Model is a 3D representation of the Earth’s surface in a digital format. Elevation is represented in a regular pixel grid of values (a “raster”). DEMs follow a “production line” to create three distinct subtypes of DEMs: Digital Surface Models (DSMs), representing the Earth’s surface including all objects on it (buildings, infrastructure, vegetation); Digital Terrain Models (DTMs), representing the Earth’s terrain without any above-ground features; and Normalized Digital Surface Models (nDSMs), representing the height of objects above the ground surface, created by subtracting the DTM from the DSM.
Different active and passive remote sensing technologies can be used to create DEMs. Passive optical sensors on satellites or aircraft take images from different angles to create 3D models of the Earth’s surface. Active emitters include Synthetic Aperture Radar (SAR) which emit radar signals that “bounce” off the Earth’s surface. LiDAR (Light Detection and Ranging) emitters use laser pulses to create highly accurate elevation data. SAR has the advantage of being unaffected by cloud cover or the day-night cycle, although challenges remain in highly undulating and heavily vegetated terrain.
Indicative Cost Range Details
DSMs and DTMs at 30m resolution (or lower) are available for free though users should be aware that underlying imagery was often acquired as early as the 2000s or 2010s. Therefore, in addition to the low spatial resolution, the surface and terrain features may have changed in the interim. Sub-10m VHR-based DSMs and DTMs come at varying price points depending on the spatial resolution or whether underlying imagery was retrieved from an archive or newly ‘tasked’. 5m archival DSMs are available from 7.00 EUR/km² whereas 0.5m DSMs can go for 55.00 EUR/km² and 0.5m DTMs for twice that.
Indicative Cost Range
Free or from ~7.00 EUR/km²